The hardest and most wear-resistant bits with the longest life. Straight flutes withstand the heavy pressure needed to penetrate hardened steel. These bits cut more aggressively and resist stress better than spiral-flute bits. Carbide stays sharp at high temperatures and faster speeds for the best performance on hard and difficult-to-machine materials. It can be brittle, however, so these bits require a rigid machine tool holder to prevent breakage and should not be used in hand drilling applications.